This invention relates to the field of carton construction. More specifically, it relates to the field of carton constructions for manufacture from corrugated paper and in particular to corrugated cartons of the center slotted container type which employ a center special slotted bottom construction. By "center special slotted container" is meant the blank of the carton is formed with unequal length bottom flaps, the carton blank being folded into a collapsed tube design and glued at the manufacturer's joint. The collapsed tube configuration is also referred to as "knock down assembly". This knock down assembly is fed to a squaring device after processing in the folder gluer machine, whereupon parallel compression edges or plates opposing each other are oscillated against the free edges of the top and bottom flaps of the glued, knock down carton assembly to "square up" the glued manufacturer's joint. At the time the blank enters this squaring device, the glued joint is not fixedly set up, that is, the adhesive is not yet dried. The combined squaring pressure of the oscillating plates and the vertically stacked weight of the succession of tubular collapsed blank delivered from the folder-gluer machine hold the glued joint square long enough for the glued joint to dry and set.
The center special slotted container (sometimes referred to hereinafter as a CSSC box) has heretofore utilized bottom flaps of a configuration such that after the blank is fabricated to a knock down assembly, the bottom flaps provide an uneven edge and upon engagement by the parallel plates of the squaring device may cause, and often does cause, the manufacturer's glue joint to set up in a condition where the joint is skewed. In the industry this condition is a defect called an "out-of-square joint" on the CSSC box. An example of a carton having uneven bottom flaps is U.S. Pat. No. 2,367,717.
It is, accordingly, an object of this invention to provide a center special slotted container which will square up in the automatic folder-gluer machinery for carton set up and will obviate the skewed glued joint in the carton made on such machinery.
It is another object of the present invention to provide an improved rectangular carton construction which includes a novel bottom and top flap configuration for closing the CSSC carton.
And, it is a further object of the present invention to use a die cut section of blank formation in line with the "Flexo" folder-gluer machine enabling formation of the blank and manufacture of the blank on a one pass operation and eliminate a second pass in the operation; the single pass operation still producing squared cartons without defects.
A still further object of the present invention is to provide a CSSC container design with a new and novel flap configuration for bottom flaps or top flaps of the carton or both in which the flaps meet in the center of the length and width, respectively, of the carton, and maintain the carton in a collapsed tubular formation such that the outwardly extending top and bottom flaps that are of the same length; thereby enabling squaring of the manufacturer's joint producing a square carton when set up.
Other objects and advantages of the invention will become apparent from the remaining portion of the specification.